In general, an electronic control system for a vehicle receives information from a variety of sensors, processes the received information, and drives a corresponding circuit and/or an actuator in such a way that appropriate control operations can be performed. There are a variety of electronic control systems, for example, an electronically-controlled suspension system, an electronically-controlled steering system, an ABS (anti-lock brake system), a TCS (traction control system), an ESP (electronic stability program), etc.
Particularly, in the electronic control system, since a device for determining a vehicle running state or a road surface condition or a device for calculating gain which determines control amount in response to a vehicle speed generates output data using vehicle speed information, the vehicle speed information must have high accuracy. Therefore, it is necessary to determine the presence or absence of a failure of the vehicle speed sensor for providing the vehicle speed information.
The electronic control system determines the presence or absence of the vehicle speed sensor failure on the basis of the information received from a plurality of sensors installed in the vehicle. More specifically, a conventional vehicle speed sensor failure detection apparatus of the electronic control system determines the presence or absence of the vehicle speed sensor failure on the basis of information received from a throttle position sensor, a brake sensor, a vehicle speed sensor and a gear position sensor.
If a TPS value of the throttle position sensor is equal to or greater than a predetermined level, a brake state is in an OFF state, a gear position is in a drive position and a vehicle speed is less than a predetermined vehicle speed, the conventional vehicle speed sensor detection apparatus determines the presence (or occurrence) of the vehicle speed sensor failure. Then, in order to avoid a danger resulting from the mis-control caused by the incorrect vehicle speed information, the conventional vehicle speed sensor failure detection apparatus stops the control operation of the electronic control system and informs a user of the control system failure occurrence.
However, some diesel vehicles or systems are not equipped with the throttle position sensor. In this case, since the electronic control system determines the presence or absence of the vehicle speed sensor failure without using information from the throttle position sensor, determining the presence or absence of the vehicle speed sensor failure is not correct which leads to the mis-control in control operations of the electronic control system using the vehicle speed information.
Further, the gear position sensor for providing gear position information may not be installed in some vehicles or systems. In this case, since the electronic control system determines the presence or absence of the vehicle speed sensor failure without using the gear position information, determining the presence or absence of the vehicle speed sensor failure is not correct which also leads to the mis-control in the control operations of the electronic control system using the vehicle speed information.